Just $1 and a Post-it Note can change a life.

Rosa's offers a taste of New York-style pizza to the people of Philadelphia.

But that's not all we serve. Rosa's and our customers work together to feed the city a taste of kindness and hope every day.

Philadelphia is the poorest large city in the country.

And it's the city with the worst deep poverty rate in the U.S., with roughly 185,000 people -- including 60,000 kids -- living on incomes below half of the federal poverty line.

Feeling hopeless? Well, we have a plan.

At Rosa's, customers can "pay it forward" by pre-purchasing slices for people in need.

Owner Mason Wartman, who left his Wall Street desk job to open the shop, says pay-it-forward pizza started with one customer, one dollar, and one Post-it note.

The customer was inspired by an Italian coffee house practice called caffè sospeso (suspended coffee), by which customers can pre-purchase cups of coffee for less fortunate customers.

Mason wrote the purchase on a Post-it and slapped it on the wall behind the register to be redeemed by the next homeless patron to enter the store.

As word spread, more and more customers participated.

And Rosa's wall blossomed with colorful notes signifying acts of kindness and a guaranteed slice for everyone who walked in, regardless of their ability to pay.

Since that first pay-it-forward slice, we have provided more than 150,000 pizza slices to homeless Philadelphians.

Pre-purchased slices now represent a whopping 10% of our business. And it's having a remarkable impact on the community, showing not only that acts of kindness can be contagious, but also how a small gesture of support can have a ripple effect of positivity.